Object-positioning linkage having a single-shaft plural-piston actuator

ABSTRACT

A pair of targets one of which is positioned in the path of a particle accelerator beam or both targets are removed from the beam path by means of a linkage which carries the targets in long vertical movements in response to short horizontal-actuating movements of dual coaxial pistons which differentially and reciprocably drive a single shaft through the short horizontalactuating movements to drive the linkage to carry the targets to one of the three positions.

United States Patent Inventor Hallo S. Clay Los Altos Hllls, Calil.

Appl. No. 10,515

Filed Feb. ll, 1970 Patented Nov. 23, 1971 Assignee The United States of America m represented by the United States Atomic Energy Commission OBJECT-POSITIONING LINKAGE HAVING A SINGLE-SHAFT PLURAL-PISTON ACTUATOR 7 Claims, 2 Drawing Figs.

U.S. Cl 313/147, 74/99 R, 92/62 Int. Cl H0lj 1/88 Field of Search 74/89, 99;

[56] References Cited UNITED STATES PATENTS 3,149,537 9/1964 Fink 92/62 X 3,412,274 11/1968 Wolf 313/l46X Primary Examiner-Raymond F. Hossfeld Altorney- Roland A. Anderson ABSTRACT: A pair of targets one of which is positioned in the path of a particle accelerator beam or both targets are removed from the beam path by means ofa linkage which carries the targets in long vertical movements in response to short horizontal-actuating movements of dual coaxial pistons which differentially and reciprocably drive a single shaft through the short horizontal-actuating movements to drive the linkage to carry the targets to one of the three positions.

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BACKGROUND OF THE INVENTION The present invention relates to object positioning linkages and actuators, and more particularly, it relates to a linkage that may be driven to a plurality of positions by a single shaft that may be reciprocated to a plurality of corresponding positions by a plurality of coaxial pistons.

Where it is necessary to provide an isolated environment, remote controls are usually provided that require physical penetration into the environment. At the points of penetration, care must be taken to prevent leaks in order to preserve the isolation. It is therefore desirable to minimize the number of connections and penetrations into the isolated environment. Furthermore, an isolated environment is often made as small as possible so as to minimize construction and operating costs and to fit into available space. Thus, the space in which a manipulating mechanism is to be operated may be very restricted. In addition, it may be required that more than one mechanism be operated in the same space. It is therefore desirable to provide mechanisms that may be retracted from a space of operation to a position that is clear of other mechanisms during their operation in the same space. It is also desirable that the space of operation be fully utilized by the manipulating mechanism so that manipulation occurs efficiently within the space provided. Furthermore, it is desirable that the mechanism be positively actuated to ensure that the intended movements of the mechanism are carried out.

SUMMARY OF THE INVENTION In brief, the present invention pertains to a remotely operable mechanism for use in a restricted space of an isolated environment for carrying an object to a plurality of positions within the space. Only a single interface into the environment is required for transmission of mechanical movement to the mechanism. In particular, a linkage having very limited horizontal movement and a large vertical movement is provided for carrying the object to any desired plurality of positions within a space that is limited in the horizontal direction. The linkage is actuated by one of a plurality of coaxially aligned pistons that positively drive a single shaft through a bellows at the interface of the environment. The shaft is connected to the mechanism within the isolated environment for moving the mechanism, and therefore the object to the desired plurality of positions selected by actuation of the pistons.

It is an object of the invention to remotely position an object in a plurality of positions in an isolated environment using only a single mechanical interface with the environment.

Another object is to remotely move objects over relatively large distances to a plurality of vertical positions with an actuator that moves only short horizontal distances.

Another object is to. positively position one of a plurality of targets in a vacuum chamber in the path of a particle accelerator beam or to remove all targets from the beam path by means of mechanism having large vertical movements and short horizontal movements and only a single mechanical interface with the chamber.

Another object is to maintain zero leakage into an isolated environment at a mechanical interface through which motion is transmitted to a mechanism within the environment.

Other objects and advantageous features of the invention will be apparent in a description of a specific embodiment thereof, given by way of example only, to enable one skilled in the art to readily practice the invention, and described hereinafter with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a schematic diagram of a linkage mechanism for alternately positioning one or the other of two targets in the path of a particle accelerator beam or removing both targets from the beam path, according to the invention.

FIG. 2 is a cross-sectional view of two pressure-operated coaxial pistons for driving a single shaft to actuate the linkage of FIG. 1 for positioning the targets.

DESCRIPTION OF AN EMBODIMENT Referring to the drawing there is shown in FIG. I a pair of targets 11 and 12 which may be mounted in an evacuated chamber 10 for positioning in the path of a particle accelerator beam 13 for comparing results of the beam on different types of targets. For example, the target 11 may be comprised of a plurality of aluminum foils through which the beam 13 successively passes while the target 12 may be a solid piece of aluminum. The target 11 is rigidly attached to one end of a link 14 while the other end of the link is pivotally connected to a horizontally reciprocable actuating shaft 15 at a pivot point 17. The target 12 is also rigidly attached to the link 14 by means of a connecting link 18. The targets 1] and 12 are carried by means of the actuating shaft 15 acting through the link 14 and additional links 19 and 20. One end of the link 19 is pivotally connected to the shaft 15 at the point 17, while the other end of the link is pivotally connected to the link 20 at a pivot point 23. The other end of the link 20 is carried in a bearing 26 in which the end of the link 20 is free to slide. The bearing 26 is pivotally connected to the link l4 at pivot point 27. The link 20 is rotatable about a stationary ground point by means of a pivotal connection 24.

In operation the targets 11 and 12 may be positioned in positions 11 and 12' so that both targets are clear of the beam 13; or they may be positioned in positions 11 and 12" with the target 12 in the path of the beam 13; or they may be positioned with the target 11 in the path of the beam and the target 12 clear of the beam path. Such positioning is accomplished by horizontal actuation of the shaft 15; with the shaft fully leftward the target 11 is in the path of the beam; with the shaft fully rightward with the pivot 17 in a position 17' the targets are in the positions 11 and 12 with both targets clear of the beam path; and with the pivot 17 in an intermediate position 17" the target 12 is in the position 12 in the path ofthe beam 13.

It will be noted that the small horizontal movements of the actuating shaft 15 produce large vertical movements of the targets 11 and 12. This occurs because of the length of the arm of the link 20 from the point 24 to the pivot 23 is very short compared to the length of the arm of the link 20 from the point 24 to the pivot 27. Thus, as the short arm is rotated to bring the pivot 23 to the points 23" and 23', it is moved over a small distance, while the sliding bearing 26 and the pivot 27 are moved successively over a large distance to positions 26 and 26' and to the points 27" and 27, rotating the link 14 thereby to successive positions 14" and 14' and the link 20 to positions 20 and 20'. Thus, it is seen that as the shaft 15 is moved horizontally over very small distances to rotate the pivot 23 through small distances, the point 27 and therefore the targets 1 1 and 12 are moved over large distances vertically to the desired positions.

It will be further noted that with the targets 11 and 12 in the positions 11 and 12 that all of the mechanisms and targets are clear of the beam 13 and the space in the upper part of the chamber 10, thereby leaving the space clear for positioning of other targets in the path of the beam.

The shaft 15 is driven and maintained in its several positions by means of an actuator 29 (FIG. 2). The shaft 15 extends through the chamber wall and is secured to a piston 30 which is mounted in a cylinder 32 for sealed sliding movement therein. A flange 33 is integral with one end of the cylinder 32 and is secured with a vacuum seal to the wall of the chamber 10. A bellows 35 is mounted between the piston 30 and the end of the cylinder 32 next to the chamber 10. The shaft 15 is guided in a bearing 36 which has a pumpout hole 37 connecting the space within the bellows with the chamber 10 for complete evacuation of the space within the bellows 35. It will be observed that the piston 30, cylinder 32 and the bellows 35 form an interface with the vacuum chamber for transmission of mechanical motion into the chamber with an arrangement that does not require any bearing surfaces at the interface.

The interface may be completely sealed to obtain zero leakage.

The piston 30 and shaft 15 are urged rightward by means of springs 40 mounted within a cylinder 42 that is secured in coaxial relationship to the outer end of the cylinder 32. The springs 40 are stretched between the piston 30 and the cylinder 42 by means of a bearing 43 held at one end of the cylinder 42 with a C-w'asher 45 bearing against a lip of a flange 46 at the outer end of the cylinder 42. With the piston 30 held rightward by the springs 40 as shown in FIG. 2, the targets 11 and 12 are maintained at positions 11 and 12' (FIG. 1).

A flanged cylinder 48 is secured in coaxial relationship to the outer end of the cylinder 42. A piston 49 is mounted in the cylinder 48 in coaxial relationship with the piston 30 for sealed sliding movement therein. A bellows 51 is sealed to and extends from one side of the piston 49 to the opposite end of the cylinder 48 to which it is also sealed. A shaft 52 also is secured to the piston 49 and extends therefrom through the cylinder 48, the bearing 43, and the cylinder 42, into engagement with the outer end of the piston'30. Connecting passages 53 are provided in the ends of the cylinders 48 and 42 so that the space within the bellows 51 connects with the space within the cylinder 42. The springs 40 acting through the piston 30 and shaft 52 tend to hold the piston 49 rightward in the position shown in FIG. 2.

in operation the targets 11 and 12 are moved from their normal positions 11' and 12' to their positions 11" and 12" by actuation of the piston 49. This is accomplished by manipulation of a valve 54 which may be operated to transfer pressurized gas from a supply 55 over a line 57 to a port 58 in a flange 59 secured to the outer end of the cylinder 48. The pressurized gas is thereby applied against the piston 49, driving it leftward along with the shaft 52 and piston 30 against the force of the springs 40. Leftward movement of the piston 49 is terminated when a pair of stops 60 that extend from the piston 49 engage the bottom of the cylinder 48. Since the pistons 30 and 49 are moved equal distances through the action of the shaft 52, the. shaft 15 is also moved an equal distance to drive the pivot point 17 from its position 17' to its position 17" thereby moving the targets 11 and 12 from positions 11' and 12 to their positions 11" and 12". Vents 61 and 62 to atmosphere are provided in the left end of the cylinders 48 and 32 respectively to prevent pressure buildup against leftward movement of the pistons 49 and 30.

To position the targets 11 and 12 in their highest vertical position, the shaft 15 is driven fully leftward by manipulating a valve 63 to supply pressurized gas from the supply 55 over a line 64 to a port 65 in the cylinder 42. Pressure is applied thereby to the piston 30 driving it fully leftward, independently of the piston 49, to a position in which stops 66 that extend from the piston 30 become engaged with the left end of the cylinder 32. The shaft 15 is thereby moved fully leftward to a position in which the target 11 is in the path of the beam 13.

To ensure return of the pistons 30 and 49 to their fully rightward position under the urging of the springs 40, vents 67 and 68 to atmosphere are provided for connection to the cylinders 42 and 48 by means of the valves 54 and 63 so that the pressurized gas within the cylinders may be relieved to permit the pistons 30 and 49 to return fully rightward.

A target positioning linkage and actuator exemplifying the invention were constructed and successfully operated. The target 11 was comprised of 20 sheets of aluminum foil, 0.020 inches thick and secured in frames to the link 14 while the target 12 was single block of aluminum 0.4 inches thick. In approximate dimensions, the length of the link 14 was 8% inches, the length of the link 20 was 7%inches, the link 19 was 3 inches long, the pivot 27 was located inches from the pivot 17 and the pivot 23 was located 1 inch from the pivot 24. The total movement of the shaft was seven-eighths inches,

while movement from the position 17' to the position 17" was five-eighths inches. The total vertical movement of the target 11 was 7% inches while the vertical movement of the targets from the positions 11 and 12 to the positions 11'' and 12" was 5% inches. The total horizontal movement of the target 11 was 3% inches while the horizontal movement of the targets from the positions 11 and 12' to the positions 11" and 12" was 2% inches. The overall length of the actuator 29 was 12 inches.

While an embodiment of the invention has been shown and described, further embodiments or combinations of those described herein will be apparent to those skilled in the art without departing from the spirit of the invention.

What I claim is l. A mechanism operable from a remote location for positively positioning an object in first, second or third vertical positions, comprising:

first, second and third links, said first and second links being pivotally connected at a first pivot point, said second and third links being connected at a second pivot point, and

said first and third links being connected together at a third pivot point, said third link being pivoted about a fourth pivot, said fourth pivot being a stationary point, said third pivot being stationary with respect to said first link and slidable with respect to said third link;

a first shaft connected to said first pivot point;

means for stopping said first shaft;

means for urging said shaft towards said stopping means to positively maintain said first shaft in a normal first horizontal position; a first piston operable for positively driving said first shaft to a second horizontal position;

a second piston coaxial with said first piston; and

a second shaft between said first and second pistons for driving said first piston with said second piston to position said first shaft in a third horizontal position that is intermediate said first and second positions, said object being carried by said first link to said first, second and third vertical positions upon said first pivot being carried to said first, second and third horizontal positions.

2. The positioning mechanism of claim 11 wherein said first shaft is integral with said first piston.

3. The positioning mechanism of claim 1 wherein said object and said first shaft are in a sealed chamber, and further including a bellows coaxially mounted around said first shaft, said bellows having one end sealed to said first piston and the other end sealed to the wall of said chamber, means for connecting the space within said chamber to the space within said bellows.

4. The positioning mechanism of claim 1 including a first stop for stopping said first piston in a position corresponding to the second position of said first shaft, and a second stop for stopping said first and second pistons in positions correspond- 1 ing to the third position of said first shaft.

5. The positioning mechanism of claim 1 wherein the distance of said third link from said fourth pivot to said second pivot is relatively short as compared to the distance from the fourth pivot to the third pivot, thereby resulting in large vertical movements of said object corresponding to short horizontal movements of first pivot point.

6. The positioning mechanism of claim 5 wherein said object comprises first and second targets integral with said first link, said first and second targets being clear of a charged particle beam with said first shaft in said first position, said first target being carried to a position in the path of said beam upon said first shaft being moved to said second position, and said second target being positioned in the path of said beam and said first target being clear of said beam upon said first shaft being moved to a third position intermediate said first and second positions of said first shaft.

7. The positioning mechanism of claim 1 wherein said second shaft is integral with said second piston, said second shaft being engageable with said first piston-to-position said first shaft in said. third horizontal position, said first piston being operable independently of said second piston to drive said first shaft to said second horizontal position. 

1. A mechanism operable from a remote location for positively positioning an object in first, second or third vertical positions, comprising: first, second and third links, said first and second links being pivotally connected at a first pivot point, said second and third links being connected at a second pivot point, and said first and third links being connected together at a third pivot point, said third link being pivoted about a fourth pivot, said fourth pivot being a stationary point, said third pivot being stationary with respect to said first link and slidable with respect to said third link; a first shaft connected to said first pivot point; means for stopping said first shaft; means for urging said shaft towards said stopping means to positively maintain said first shaft in a normal first horizontal position; a first piston operable for positively driving said first shaft to a second horizontal position; a second piston coaxial with said first piston; and a second shaft between said first and second pistons for driving said first piston with said second piston to position said first shaft in a third horizontal position that is intermediate said first and second positions, said object being carried by said first link to said first, second and third vertical positions upon said first pivot being carried to said first, second and third horizontal positions.
 2. The positioning mechanism of claim 11 wherein said first shaft is integral with said first piston.
 3. The positioning mechanism of claim 1 wherein said object and said first shaft are in a sealed chamber, and further including a bellows coaxially mounted around said first shaft, said bellows having one end sealed to said first piston and the other end sealed to the wall of said chamber, means for connecting the space within said chamber to the space within said bellows.
 4. The positioning mechanism of claim 1 including a first stop for stopping said first piston in a position corresponding to the second position of said first shaft, and a second stop for stopping said first and second pistons in positions corresponding to the third position of said first shaft.
 5. The positioning mechanism of claim 1 wherein the distance of said third link from said fourth pivot to said second pivot is relatively short as compared to the distance from the fourth pivot to the third pivot, thereby resulting in large vertical movements of said object corresponding to short horizontal movements of first pivot point.
 6. The positioning mechanism of claim 5 wherein said object comprises first and second targets integral with said first link, said first and second targets being clear of a charged particle beam with said first shaft in said first position, said first target being carried to a position in the path of said beam upon said first shaft being moved to said second position, and said second target being positioned in the path of said beam and said first target being clear of said beam upon said first shaft being moved to a third position intermediate said first and second positions of said first shaft.
 7. The positioning mechanism of claim 1 wherein said second shaft is integral with said second piston, said second shaft being engageable with said first piston-to-position said first shaft in said third horizontal position, said first piston being operable independently of said second piston to drive said first shaft to said second horizontal position. 